Flushing pigments



Patented Jan. 27, 1942 21271523 FLUSHING PIGMENTS Edward G. Yee, Chicago, Ill., assignor to The Sherwin-'Williams Company, Cleveland, .Ohio, a corporation of Ohio No Drawing. Application October 5, 1939,

Serial No. 298,055

Claims.

The piment invention relates to improvements in the manufacture of non-aqueous pigment dispersions in a liquifiable vehicle, and particularly to the transfer of aqueous pigment pulps directly into organic vehicles by anoperation or process known to those skilled in the arts as flushing. It has special reference to agents for effecting and/or facilitating the transfer.

It is well known that some pigmentsmay be There is a frequent tendency of the vehicle and be removed by other means. One use of the flushin agent is to minimize or prevent the for mation of emulsion.

Pigments particularly suitable for flushing in flushed with oil without an added flushing agent... it) accordance with this invention are iron blues, For example, aqueous white lead is readily chrome yellows, organic lakes and pigment dyefiushed into linseed oil by simply mixing the two stuffs. 4 materials. Pigments in this class are usually hy- The vehicle may be any water-immiscible liqdrophobic in character. It is also known that uid or solid which is or'becomes liquid at the certain agents-facilitate the flushing operation, temperature of operation. It may be selected or even bring it about in the case of certain comfrom coal tar solvents, mineral spirits, or hy; binations of pigment and receiving vehicle. Pigdrogenated naphthas, representing the volatile ments which do not flush readily or which do not vehicles, or from linseed oil, China wood oil, soya flush without an added flushing agent are usually bean oil, perilla oil, other vegetable and animal .hydrophilic in character. Various explanations oils, oleoresinous varnishes or synthetic varnishes are given for the success of such agents or class representing the drying vehicles, or mineral oil, of agents and for the failure of chemically simipetrolatum, castor oil or waxes, representing the lar compounds. Some of these explanations ii'inon-drying vehicles. All tliese may be used in volve the physical nature of the molecule as well the present invention. The: drying oils ordinaras its chemical reactivity. ily have an acid number, representing a content The present invention is based upon the disof fatty acid which may form a soap with the covery that a group of amines .not heretofore amine flushing agent. The formation of the known as flushing agents, are useful as'such. soap does not render the amine ineffective, for The value of the invention lies. inthe facts that the amine agent may be added effectively as a only a small quantity is needed to eifectthe soap or as the free amine. The amine may be transfer, and that the flushing agent is relativecondensed with soap-forming fatty acids such as 1y inexpensive. oleic, stearic, palmitic, linolenic, or ricinoleic The object of the present invention is to use acid, or with soap-forming resin acid, such as as flushing agents, amines or their soaps with rosin or abietic acid, to form the amine soap fatty acids, having th essential grouping flushing agent.

011F011, Because the free amine or its soaps may be CH: used with vehicles which are volatile or which V possess no acid number, it is known that both CHI-0B1 R1 the free amine and its soapsare flushing agents.

where R1 and B: may be hydrogen, methyl, ethyl, 40 While soap formation is not essential for the phenyl or cyclohexyl groups or combinations P t e Of s invention, l t c d ty in 611-1 thereof. tral vehicles adds to the effectiveness of the It is also an object of the invention to form amine flushing gent. Where e acid is of 8 pigment characterized by the presence of a cys w ns Chara-Chir- T u s. fattyecids. clohexylamine flushing-agent. other soap-forming acids may be added.

Other. and ancillary objects and advantages ples are given below to illustrate t s in-' will appear from thefollowing, description and t ,While e e e p s al mainly with explanation of the invention. iron blue pigments, its usefulne is not restricted The invention may be used with both inorganic o s II'OII e (ferric ferrocyanide) is highand organic pigments. The act of flushing inlyhydrophilic and is one of the most difficult ,volves' intimate mixing of the aqueous pigment pigments to employ in a flushing process. Therepulp and the receiving vehicle at a considerable fore, the invention is illustrated largely by refexpenditure of time and power. A flushing agent erence to it, as it is the severest test found to quickens the process and saves time and money. measure the comparative effectiveness of the flushing agents.

some of the flushing agent.

EXAMPLE I.Printing base ink Pounds Water-wet iron blue presscake containing 500 lbs. of the pigment (dry basis) 2000 Litho varnish (a heat-bodied linseed oil varnish) 500 Cyclohexylamine 13 means, and about one-third of the remaining presscake is added to the mixer. 50'lbs. of litho varnish and 2 lbs. of cyclohexylamine are also added. On further mixing, more water is flushed out. The remaining presscake is flushed out in two charges in the above manner, using 2 lbs. of cyclohexylamine and 50 lbs. of litho varnish in each charge. When all the presscake is flushed, steam is turned on and the temperature of the mass raised to 5060 C. .Vacuum is applied to the mixer and mixing is continued under reduced pressure until the pigment-oil paste is substantially water-free. The mass is cooled and the remaining 100 lbs. of litho varnish added to make a base ink containing one part of pigment to one part of varnish. This is a typical procedure for the practice of this invention, but it is not limited to such. Those skilled in the art may vary it for their particular need. Instead of vacuum drying, the paste may be finished on a roller mill. The time cycle for this procedure is about four hours.

It is-not necessary to conduit the process in stages as above described, but such procedure is more efiicient than in conducting t e entire operation On all the materials, as is well known. The removal of water may or may not remove Some of the forms are soluble in water,'but also more soluble in the flushing vehicles, so that with the amounts given for the procedure given, there is sufllcient of the agent present.

Any device that .Exsuru: V

Pounds Water-wet peacock blue (a standard organic lake) presscake containing 500 lbs. of the pigment (dry basis) 2000 Mineral oil 500 Cyclohexylamine oleate Procedureis similar to that of Example I. The mineral oil and cyclohexylamine oleate are added, as needed, to flush the pigment.

basis) 3000 Cyclohexylamine l0 Linseed oil 600 Procedure is similar to that of Example I.

EXAMPLE VII Pounds Water-wet iron blue presscake containing 600 lbs. of the pigment (dry basis) 2000 Mineral spirits 600 Glycerol-phthalate varnish, 100% solids 800 Cyclohexylamine 25 Exmu: II

Pounds Water-wet iron blue presscake containing 600 lbs. of the pigment (dry basis) 2400 Linseed l 600 N-methyl cyclohexylamine 20 The procedure is similar to that of Example I.

'Exmptn m Pounds Water-wet iron blue presscake containing 500 lbs. of the pigment (dry basis) 2000 Castor oil I 500 Cyclohexylamine 12 Procedure is similar to that f Example I.

EXAMPLE IV Pounds Water-wet phospho-tungstate rhodamine lake containing 600 lbs. of the pigment (dry basis) 2000 Litho varnish N-ethyl cyclohexylamine oleate 4 Procedure is similar to that of Example I.

The pigment is flushed in the glycerolphthalate varnish with cyclohexylamine similar" to Example I. The mass is vacuum dried and cooled, and the mineral spirits added.

EXAMPLE VIII Pounds Water-wet toluidine red toner presscake containing 600 lbs. of the pigment (dry basis) 2000 Ester gum varnish solids)"; 600

Mineral spirits 400 Phenyl-cyclohexylamine oleate 10 EXAMPLE IX Pounds Water-wet Lithol Red R presscake containing'500 lbs. of the pigment (dry basis) 2000 Procedure is similar to that of Example I.

The. foregoing examples establish that the amine may be primary, secondary, or tertiary, so long as it has at least one cyclohexyl radical. This establishes that the effective grouping is CaHu.N= in a free amine or in an amine soap. The agents may have solubility in water, but are generally more soluble in the liquid vehicle. The removal of water from the mass after a flushing operation may remove some of the agent. However, where the operation is conducted in one step, its main function has been performed. Where the operation is carried out in several steps, more of the agent is added, .so that any removal of some of the agent in the withdrawn water cannot be effective to deplete the process of the agent.

The pastes prepared in the manner described are suitable for the manufacture of all types of protective and decorative finishes and for allied uses.

The quantity of flushing agent required for a given result varies with the apparatus used, the pigment, the pulp concentration, the receiving vehicle and other factors. It is a small. quantity, commonly less than 5% of the dry weight of pigment.

q The practice may be varied in accordance with the scope of the invention as expressedj-n the appended claims.

I claim: Y

1. The method of flushing pigment particles from aqueous paste form into a liquid vehicle immiscible with water to release water, which comprises agitating a mass of aqueous pigment paste with a receiving liquid vehicle which is immiscible with water, in the presence of a small quantity of a cyclohexylamine compound having the grouping therein with the formula in which R1 and R2 may be selected from the group consisting of hydrogen, and the radicals:

methyl, ethyl, phenyl and cyclohexyl.

CaHh-N in which Rrand R2 may be selected from the 3 group consisting of hydrogen, and the'radicals; methyl, ethyl, phenyl and cyclohexyl.

3. The method of flushing pigment particles from aqueous paste form into a' liquid vehicle immiscible with water to release water, which comprises agitating a mass of aqueous pigment Y paste with a receiving liquid vehicle which is immiscible with water,in the presence of a small quantity of a cyclohexylamine soap of a cyclohexylamine of the formula CaYrTu-N in which R1 and R2 may be selected from the group consisting of hydrogen, and the radicals: methyl, ethyl, phenyl and cyclohexyl, and a soapforming acid selected from the group eof soap- ,forming resin acids and soap -forming fatty acids.

4. The method according to claim 1 in which.

the receiving liquid contains a drying vehicle for pigment. I

5. The method according to claim 1. in which the receiving liquid is anon-drying vehicle for pigment. I g

6. The method according to claim 1 in which the receiving vehicle is volatile.

'7. The method according to claim 1 in which one of the attachments R1 and R2 is hydrogen.

8. The method according to claim 1 in which the compound is cyclohex'ylamine.

9. The method of claim l in which the receiving liquid is litho varnish.

10. The method of claim 1 in which the ment is iron blue.

EDWARD G. YEE. 

